Modulating MAPbI3 perovskite solar cells by amide molecules:Crystallographic regulation and surface passivation

A controllable crystallization is of practical importance to produce high-quality perovskite thin films with reduced structural defects.Lewis bases as electron-pair donor chemicals can strongly coordinate to lead ions and have been extensively employed to manipulate the growth of perovskite crystals.In this work,we demonstrate a series of Lewis-base amides,for morphological regulation of methylammonium lead triiodide(MAPbI3)thin films.The screened acetamide was demonstrated to decently improve the grain size,along with a spatial distribution at grain boundaries(GBs).The mesostructured solar cells of acetamide-modified absorbers yielded an optimized power conversion efficiency(PCE)of 20.04%with a mitigated open-circuit voltage(V_(OC))deficit of 0.39 V.This work provides a facile and cost-effective strategy toward controllable fabrication of high-performance MAPbI3 solar cells.

A one-pot method for controlled synthesis and selective etching of organic-inorganic hybrid perovskite crystals

Organometal halide perovskites have recently emerged with a huge potential for photovoltaic applications. Moreover, preparation of high-quality perovskite crystals with controlled morphology is of great significance for the fundamental studies such as optical and electrical properties, as well as the applications. Here, we report a one-pot solvothermal process to synthesize sheet-shaped CH3NH3PbBr3 single crystals with the lateral size of 100 μm and the thickness of 3–8 μm. Furthermore, a controlled etching behavior on the crystalline surface was demonstrated, which could be the irregular collapse of the crystalline surface caused by the local accumulation of methylammonium cations. Using this technique,CH3NH3PbBr3 single crystal sheets could be used in the various optoelectronic devices, such as nanolaser,optical sensors, photodetectors and field effect transistors.

Remarkably enhanced water splitting activity of nickel foam due to simple immersion in a ferric nitrate solution

The development of a facile method to construct a high-performance electrode is of paramount importance to the application of alkaline water electrolysis. Here, we report that the activity of nickel foam （NF） towards the oxygen evolution reaction （OER） can be enhanced remarkably through simple immersion in a ferric nitrate （Fe（NOs）s） solution at room temperature. During this immersion process, the oxidation of the NF surface by NOs- ions increases the near-surface concentrations of OH- and Ni2＋, which results in the in situ deposition of a highly active amorphous Ni-Fe hydroxide （a-NiFeOxHy） layer. Specifically the OER overpotential of the NF electrode decreases from 371 mV （bare NF） to 270 mV （@10 mA-cm-2 in 0.1 M KOH） after immersion in a 20 mM Fe（NOs）s solution for just I min. A longer immersion time results in further increased OER activity （196 mV@10 mA,cm-2 in 1 M KOH）. The overall water splitting properties of the a-NiFeOxHy@NF electrode were evaluated using a two-electrode configuration. It is worth noting that the current density can reach 25 mA.cm-2 in 6 M KOH at an applied voltage of 1.5 V at room temperature.

BiOI Nanosheets Grown by Chemical Vapor Deposition and Its Conversion to Highly Efficient BiVO4 Photoanode

Bismuth vanadate （BiVO4） has been identified as one of the excellent visible-light-responsive photoanode for use in the photoelectrochemical water splitting. Recently intense research efforts have been devoted to the development of highly efficient BiVO4 photoanode. Herein, we reported a low-cost and scalable method for preparing nanostructured BiVO4 film. A much enhanced photocurrent （1.5 mAocm 2） was obtained for such film, which was 6.5 times higher than that of planar film at 1.23 V [vs. RHE （Reversible Hydrogen Electrode）]. The method provides an eco-friendly, reproducible and facile way to scale up on different substrates with attractive potential.

Hierarchical structure engineering of brookite TiO2 crystals for enhanced photocatalytic and external antitumor property

Here we report a hydrothermal approach to build and tailor the hierarchical structure of brookite TiO_2 crystal under multiple hierarchical scales. Benefiting from the hierarchical structure and the existence of oxygen vacancy,these as-prepared hierarchical brookite TiO_2 crystals can not only enhance photocatalytic activity, but also demonstrate their potential in the treatment of superficial malignant tumor.

Carbon-encapsulated heazlewoodite nanoparticles as highly efficient and durable electrocatalysts for oxygen evolution reactions

The activity and durability of electrocatalysts are important factors in their practical applications, such as electrocatalytic oxygen evolution reactions （OERs） used in water splitting cells and metal-air batteries. In this study, a novel electrocatalyst, comprising few-layered graphitic carbon （-5 atomic layers） encapsulated heazlewoodite （Ni3S2@C） nanoparticles （NPs）, was designed and synthesized using a one-step solid phase pyrolysis method. In the OER test, the Ni3S2@C catalyst exhibited an overpotential of 298 mV at a current density of 10 mA·cm^-2, a Tafel slope of 51.3 mV·dec^-1, and charge transfer resistance of 22.0 Ω, which were better than those of benchmark RuO2 and most nickel- sulfide-based catalysts previously reported. This improved performance was ascribed to the high electronic conductivity of the graphitic carbon encapsulating layers. Moreover, the encapsulation of graphitic carbon layers provided superb stability without noticeable oxidation or depletion of Ni3S2 NPs within the nanocomposite. Therefore, the strategy introduced in this work can benefit the development of highly stable metal sulfide electrocatalysts for energy conversion and storage applications, without sacrificing electrocatalytic activity.

Hydrophobic 1-octadecanethiol functionalized copper catalyst promotes robust high-current CO_(2) gas-diffusion electrolysis

The electrocatalytic reduction of CO_(2) presents a promising strategy in addressing environmental and energy crisis.Significant progress has been achieved via CO_(2) gas diffusion electrolysis,to react at high selectivity and high rate.However,the gas diffusion layer(GDL)of the gas diffusion electrode(GDE)still suffers from low tolerance and limited active sites.Here,the hydrophobic 1-octadecanethiol molecular was functionalized over the Cu catalyst layer of the GDE,which simultaneously stabilizes the GDL and exposes abundant active solid-liquid-gas three-phase interfaces.The resultant GDE exhibits multi-carbon(C_(2+))product selectivity over faradaic efficiency(FE)of 70.0%in the range of 100 to 800 mA·cm^(-2),with the peak FE^(c2+)of 85.2%at 800 mA·cm^(-2).Notably,the strengthened GDE could continuously drive high-current electrolysis for more than 100 h without flooding.This work opens a new way to improve CO_(2) gas diffusion electrolysis via surface molecular engineering.

Deposition of SnO2 on the Anatase TiO2 {105} Facets with High Photocatalytic Performance

Anatase TiO2 as a promising photocatalyst has been widely employed in the decontamination treatment of polluted water, air purification and water splitting. Coupling TiO2 with other semiconductor materials could further enhance the photocatalytic activity. Here, we successfully synthesized the SnOz/TiO2 catalyst by depositing SnO2 particles on the anatase TiO2 {105} facets through a gas phase oxidation process. The SnOz/TiO2 catalyst shows higher photocatalytic activity for decomposition of MB than that of the pure YiO2 catalyst. The enhanced photo- catalytic activity can be attributed to the efficient charge separation since TiO2 and SnO2 catalyst have staggered energy level.